Setting helmet rotor/cap gap

3

39topless

Well-known member
Is there a "how to" manual or instruction sheet that will help me set the gaps on my two new caps on a '39 helmet? I have the distributor off and with the coil and the opposite cap removed, I still can not access all the cap to rotor contacts with a feeler gauge to set the gaps.
Thank you,
Phil
 
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Re: Setting helmit rotor/cap gap

I think your referencing the points. You will need to remove the distributor from the car to gap the points.
 
Re: Setting helmit rotor/cap gap

39topless said:
Is there a "how to" manual or instruction sheet that will help me set the gaps on my two new caps on a '39 helmet? I have the distributor off and with the coil and the opposite cap removed, I still can not access all the cap to rotor contacts with a feeler gauge to set the gaps.
Thank you,
Phil
Click to expand...

"cap to rotor contacts" ??? Are you referring to the inner cap to rotor contact clearance? I never knew there was an adjustment procedure for doing this....
 
Re: Setting helmit rotor/cap gap

Yes there is a Ford Spec. for the rotor to inner cap terminals but the Spec is there to let mechanics know that Ford did not want this gap to open and if it did it could cause problems. If you have a new rotor and new inner caps on both sides, Check one of the terminals on each side if they are good you can assume by viewing at the others they are also good. There is no adjustment. Do make sure the rotor does not touch any of the inner cap terminals.
 
Re: Setting helmit rotor/cap gap

petehoovie said:
"cap to rotor contacts" ??? Are you referring to the inner cap to rotor contact clearance? I never knew there was an adjustment procedure for doing this....
Click to expand...

Yes, the new caps came with an instructed setting of .003-.005 for the gap where they meet the rotor contact. As you know, with new caps, before cranking the engine with the new caps installed, it is important to first check the clearances with the rotor to avoid damage. I removed the distributor. When I received the new caps, I first blackened the face of each contact with a marker. I then marked one cap L and the other R, positioned them in the distributor and, turning the rotor by hand, found that at least one contact on each cap required some filing down to keep them from touching the rotor contact. The black on those two contacts had been scraped by the rotor contact. I filed those two contacts down until they no longer touched the rotor contacts.
The instruction sheet that came with the new caps said to set (file?) the clearance gaps of the cap to rotor contacts at between .003 and .006.
I can not get the feeler gauge on all of the contact points even with the coil and the opposite cap removed in order to check these clearances.
If the contacts aren't actually touching each other as the rotor turns, is that good enough?
Thanks, Phil
 
Re: Setting helmit rotor/cap gap

Phill said: "If the contacts aren't actually touching each other as the rotor turns, is that good enough?"

I would think so....
 
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39topless
I had a real bad problem last year with the inner caps on my 32. It uses the 39-41 distributor. It turned out the issue was the aftermarket caps that I purchased, and was very difficult to pinpoint. The engine would start & run real well, until the rpm was above 3000, then it would miss/vibrate terribly. Getting new Ford caps solved my problem. I got them from Joblot in New York.
 
Kahuna said:
39topless
I had a real bad problem last year with the inner caps on my 32. It uses the 39-41 distributor. It turned out the issue was the aftermarket caps that I purchased, and was very difficult to pinpoint. The engine would start & run real well, until the rpm was above 3000, then it would miss/vibrate terribly. Getting new Ford caps solved my problem. I got them from Joblot in New York.
Click to expand...

I'm having the same type of problem. My new inner caps came from C & G. Per your suggestion, I'll , order a set from Joblot and see what happens. I've taken that damn distributor off and put it back on so many times I can do it in the dark. Thanks for the help.
 
Kinda a typical issue with all ignitions systems over the years. Many rotor must be matched for the system it is being used on. Later vehicles even had a emission rotor (E) for less radio noise suppression as overall radio noise suppression was becoming a problem with tele communications etc. I used to as a kid know when a certain 56 Ford was driving by our house out in the country because it mess up my cartoons ... Never did like that car !!!
It is important that the cap and rotor comes from the same manufacture for correct clearance. As spark jumps the gap there is a certain amount of errosion of the rotor tip etc.
As a rebuilder of the helmet distributor we measure each rotor for correct tip length to assure the wear isnt excessive, if it is we throw it away.......

In reality this gap can be pretty wide or narrow with little effect up to spark plug gap. If the plugs are gapped at .025 then rotor gap cant exceed .025 without a problem.
The Ford rotor is not insulated very well on the helmets and the plastics cant handle excessive coil output without breaking down.
The smallest gap without hitting is desired.....
 
Slightly off topic, but I recall reading literature pertaining to eliminating radio interference, whereby you build up the inner cap terminals with solder, refit caps, and turn the distributor, allowing the rotor to 'cut' a track through the soldered terminals, giving a real close fit.
 
on military vehicles we have suppressors on plug wires and generator to take out the radio interference, like the vehicle tank i own
 
Brian said:
Slightly off topic, but I recall reading literature pertaining to eliminating radio interference, whereby you build up the inner cap terminals with solder, refit caps, and turn the distributor, allowing the rotor to 'cut' a track through the soldered terminals, giving a real close fit.
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Yep the closer the gap the less spark splash or arc. The delco rotors have a E stamped into the rotor tip to help prevent this electrical interferance etc.
They actually had a few of the first computer controlled cars that missed when the wipers were turned on....:eek:
 
39topless said:
I'm having the same type of problem. My new inner caps came from C & G. Per your suggestion, I'll , order a set from Joblot and see what happens. I've taken that damn distributor off and put it back on so many times I can do it in the dark. Thanks for the help.
Click to expand...

Unfortunately, JobLot is no more.
 
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